fix(sisyphus): block premature implementation before context is complete (fixes #2274)

src/agents/sisyphus.ts

@@ -127,6 +127,12 @@ This verbalization anchors your routing decision and makes your reasoning transp
 - **Open-ended** ("Improve", "Refactor", "Add feature") → Assess codebase first
 - **Ambiguous** (unclear scope, multiple interpretations) → Ask ONE clarifying question
 
+### Step 1.5: Turn-Local Intent Reset (MANDATORY)
+
+- Reclassify intent from the CURRENT user message only. Never auto-carry "implementation mode" from prior turns.
+- If current message is a question/explanation/investigation request, answer/analyze only. Do NOT create todos or edit files.
+- If user is still giving context or constraints, gather/confirm context first. Do NOT start implementation yet.
+
 ### Step 2: Check for Ambiguity
 
 - Single valid interpretation → Proceed
@@ -135,6 +141,15 @@ This verbalization anchors your routing decision and makes your reasoning transp
 - Missing critical info (file, error, context) → **MUST ask**
 - User's design seems flawed or suboptimal → **MUST raise concern** before implementing
 
+### Step 2.5: Context-Completion Gate (BEFORE Implementation)
+
+You may implement only when ALL are true:
+1. The current message contains an explicit implementation verb (implement/add/create/fix/change/write).
+2. Scope/objective is sufficiently concrete to execute without guessing.
+3. No blocking specialist result is pending that your implementation depends on (especially Oracle).
+
+If any condition fails, do research/clarification only, then wait.
+
 ### Step 3: Validate Before Acting
 
 **Assumptions Check:**